You're correct of course. And I know it has been produced with the bigger coronet. I included this picture in my review:
However this dial seems to be very rare, I haven't seen many of them around.
The rep dial (my old 1680 on the left) is indeed quite close, but the rep SUBMARINER font is different enough to be easily spotted every time, regardless of the color tone. Or have you ever seen the red Sub with the font that doesn't use the straight "S" (like the one below)?
I have seen modern subs with the font that uses "straight S"... and I have also seen them with the other font (that's used on the rep). But never, ever a red 1680. Even the largest example of the font you posted is clearly lower than on the rep (plus completely different font). For me this is a giveaway (unless proven otherwise), others might see it as a meaningless detail.